127 lines
3 KiB
Go
127 lines
3 KiB
Go
package utils
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import (
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"bytes"
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"fmt"
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"io"
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"os"
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"os/exec"
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"os/signal"
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"path/filepath"
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"strings"
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"syscall"
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"github.com/Sirupsen/logrus"
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)
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// PRSetChildSubreaper is the value of PR_SET_CHILD_SUBREAPER in prctl(2)
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const PRSetChildSubreaper = 36
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// ExecCmd executes a command with args and returns its output as a string along
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// with an error, if any
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func ExecCmd(name string, args ...string) (string, error) {
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cmd := exec.Command(name, args...)
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var stdout bytes.Buffer
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var stderr bytes.Buffer
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cmd.Stdout = &stdout
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cmd.Stderr = &stderr
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err := cmd.Run()
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if err != nil {
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return "", fmt.Errorf("`%v %v` failed: %v (%v)", name, strings.Join(args, " "), stderr.String(), err)
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}
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return stdout.String(), nil
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}
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// ExecCmdWithStdStreams execute a command with the specified standard streams.
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func ExecCmdWithStdStreams(stdin io.Reader, stdout, stderr io.Writer, name string, args ...string) error {
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cmd := exec.Command(name, args...)
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cmd.Stdin = stdin
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cmd.Stdout = stdout
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cmd.Stderr = stderr
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err := cmd.Run()
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if err != nil {
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return fmt.Errorf("`%v %v` failed: %v", name, strings.Join(args, " "), err)
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}
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return nil
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}
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// SetSubreaper sets the value i as the subreaper setting for the calling process
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func SetSubreaper(i int) error {
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return Prctl(PRSetChildSubreaper, uintptr(i), 0, 0, 0)
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}
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// Prctl is a way to make the prctl linux syscall
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func Prctl(option int, arg2, arg3, arg4, arg5 uintptr) (err error) {
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_, _, e1 := syscall.Syscall6(syscall.SYS_PRCTL, uintptr(option), arg2, arg3, arg4, arg5, 0)
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if e1 != 0 {
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err = e1
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}
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return
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}
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// CreateFakeRootfs creates a fake rootfs for test.
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func CreateFakeRootfs(dir string, image string) error {
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if len(image) <= 9 || image[:9] != "docker://" {
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return fmt.Errorf("CreateFakeRootfs only support docker images currently")
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}
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rootfs := filepath.Join(dir, "rootfs")
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if err := os.MkdirAll(rootfs, 0755); err != nil {
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return err
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}
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// docker export $(docker create image[9:]) | tar -C rootfs -xf -
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return dockerExport(image[9:], rootfs)
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}
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func dockerExport(image string, rootfs string) error {
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out, err := ExecCmd("docker", "create", image)
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if err != nil {
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return err
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}
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container := out[:strings.Index(out, "\n")]
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cmd := fmt.Sprintf("docker export %s | tar -C %s -xf -", container, rootfs)
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if _, err := ExecCmd("/bin/bash", "-c", cmd); err != nil {
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err1 := dockerRemove(container)
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if err1 == nil {
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return err
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}
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return fmt.Errorf("%v; %v", err, err1)
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}
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return dockerRemove(container)
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}
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func dockerRemove(container string) error {
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_, err := ExecCmd("docker", "rm", container)
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return err
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}
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// StartReaper starts a goroutine to reap processes
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func StartReaper() {
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logrus.Infof("Starting reaper")
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go func() {
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sigs := make(chan os.Signal, 10)
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signal.Notify(sigs, syscall.SIGCHLD)
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for {
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// Wait for a child to terminate
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sig := <-sigs
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logrus.Infof("Signal received: %v", sig)
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for {
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// Reap processes
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cpid, _ := syscall.Wait4(-1, nil, syscall.WNOHANG, nil)
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if cpid < 1 {
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break
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}
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logrus.Infof("Reaped process with pid %d", cpid)
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}
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}
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}()
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}
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